patman: Move to absolute imports

At present patman sets the python path on startup so that it can access
the libraries it needs. If we convert to use absolute imports this is not
necessary.

Move patman to use absolute imports. This requires changes in tools which
use the patman libraries (which is most of them).

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/binman/ftest.py b/tools/binman/ftest.py
index a11675d..5e24920 100644
--- a/tools/binman/ftest.py
+++ b/tools/binman/ftest.py
@@ -29,10 +29,10 @@
 from binman.etype import fdtmap
 from binman.etype import image_header
 from image import Image
-import command
-import test_util
-import tools
-import tout
+from patman import command
+from patman import test_util
+from patman import tools
+from patman import tout
 
 # Contents of test files, corresponding to different entry types
 U_BOOT_DATA           = b'1234'